I have a 1988 244 Dl M47 that had ran synthetic Ams Oil with the Volvo filter since 75000 and it now has 165000 almost. I have been changing the oil every 2500 miles. I have been told by several people that this is overkill. I'm not sure if they know that it takes me five monts to go 3 thousand miles in my car, so is the oil already broke down by the time it reaces that magic number even though its synthetic? How often do other people change their oil? I also have no plans on ever selling the car, so I willing to change the oil at closer intervals if it means that I can get 400k and hopefully more instead of only 300k out of the engene. I have kind of heard that things start to go down hill at 300k so I'm trying to do everything I can to prevent that. Any suggestions?

Also, how the Volvo fileter compare with the Mann. If there is no difference why would people spen the extra $1.50 for the Volvo one? I did have a Volvo one come with a leak at one time. Still the best filter for the car?
Thanks and Happy Bricking?